|Sexually Transmitted Diseases (STD) Prevention: New Challenges, New Approaches (AIDSCAP/FHI - USAID, 1996, 47 p.)|
by Q. Monir Islam
Women wait their turn at a clinic in Dar es Salaam, Tanzania. (Sean Sprague/Panos Pictures)
Every year close to 333 million people worldwide contract a sexually transmitted disease (STD). Ranking among the top five diseases for which adults in developing countries seek health care, STDs are nearly as common as malaria.
Until recently, despite the overwhelming evidence of their devastating impact on the health of women, children and youth, STDs have largely been ignored. Governments and international organizations are beginning to pay more attention to STDs such as gonorrhea, syphilis and chlamydial infection because of their role in enhancing another sexually transmitted infection, HIV.
STD control is, however, important in its own right. As a result of unrecognized and untreated STDs, women suffer severe complications such as pelvic inflammatory disease (PID), ectopic pregnancy and infertility; men become sterile; and newborns are left blind. The majority of STDs are curable and all of them are preventable.
Prevalence and Impact
At least two dozen microbial agents and parasites can be transmitted by sexual contact. The best-known STD, HIV, strikes more than 2.7 million people a year-but that is only a small portion of the hundreds of millions of annual STD cases.
Many STDs produce similar signs and symptoms. The most common STDs are the genital ulcer diseases - syphilis, chancroid and herpes - and those that cause vaginal or urethral discharge (gonorrhea, chlamydial infection and trichomoniasis). Reliable data about STDs in the developing world are scarce, but studies among women attending antenatal, family planning or gynecological clinics in some countries have found prevalence rates of almost 20 percent for gonorrhea and syphilis and up to 30 percent for trichomoniasis.
Young women are particularly vulnerable to STDs, but high rates of STDs are found among youth of both sexes. It is estimated that in developing countries, one in 20 youth contracts an STD each year and one-third of all STDs occur among 13- to 20-year-olds. Young people are at risk of serious complications of infection because they rarely have access to STD information and services (see page 21).
Young people around the world are at risk of serious STD complications because they rarely receive adequate prevention education. (P. Almasay/WHO)
The World Bank estimates that for women 15 to 44 years old in developing countries, STDs not including HIV are the second leading cause of years of healthy life lost, after maternal morbidity and mortality. In men of the same age, HIV infection ranks first, before tuberculosis, motor vehicle injuries, and homicide and violence. All STDs, including HIV/AIDS, account for nearly 15 percent of years of healthy life lost in this critical age group.
STDs in the Developing World
Numerous prevalence surveys confirm that although STDs are a major public health problem worldwide, STD prevalence is highest in the developing world. Rates of syphilis among women, for example, may be up to 100 times higher in developing countries than industrialized countries.
The main reasons for these differences between developed and developing countries are poverty, lack of information about STDs and limited access to care. Poverty affects STD risk because a lack of employment opportunities in rural areas forces men to move to the cities for work. The resulting concentrations of men away from home quickly lead to increased demand for sexual services. While men living apart from their families develop casual liaisons with sex workers, the women at home often have to turn to sex work to subsidize their incomes.
Economic and gender inequality also contribute to the higher rate of STDs among women in developing countries. In many cultures, women in both permanent and casual relationships have little or no control over the sexual behavior of their male partners and the use of condoms to prevent STD/HIV or pregnancy.
In addition, many women have symptomless STDs, do not recognize symptoms of STD or are too embarrassed to seek treatment. Stigmatization of people with STDs and cultural norms that discourage women from talking about sex or sexuality impede them from seeking the care they need even when it is available.
Maternal and Child Health
The burden of most STD complications falls on women and children. The consequences of STDs are more serious in women because of the risk of infections ascending the reproductive tract, leading to PID, infertility and ectopic pregnancy, and because the infections can be transmitted to their children during pregnancy and childbirth.
Gonorrhea and chlamydial infection cause most PID, which involves inflammation of the uterus, fallopian tubes, ovaries or other pelvic structures. In some parts of Africa, the yearly incidence of PID has been estimated at 360 cases per 100,000 population. Without treatment, 55 to 85 percent of women with PID may lose their fertility-often without ever realizing they had the disease.
By permanently scarring and narrowing the fallopian tubes, PID increases the risk of ectopic pregnancy. The rate of ectopic pregnancy in Africa is about three times that found in industrial countries and remains an important cause of maternal mortality, especially in rural areas where access to critical care facilities is often lacking. Studies in developing countries have found that 1 to 15 percent of all maternal mortality is due to ectopic pregnancy.
Certain strains of the sexually transmitted human papillomavirus (HPV) can also lead to death in women. Worldwide, about 250,000 women die of cervical cancer annually.
STDs in women are a frequent cause of fetal loss and infant morbidity. They can result in spontaneous abortion, prematurity, low birth weight and stillbirth and can be passed on to unborn children, resulting in congenital syphilis, ophthalmia neonatorum (eye infections that, if untreated, can lead to blind-ness) and chlamydial neonatal pneumonia.
Obstacles to Care
Complications of STDs are more severe in the developing world because many people delay seeking treatment for sexually transmitted infections. Often people-particularly women-are not aware that they have an STD because they have no symptoms; others know they are infected but avoid seeking care because of the stigma associated with STDs. Many of those who do seek treatment self-medicate, and others go to traditional healers.
Why do people delay seeking treatment even when they recognize STD symptoms and have access to care? Some have no confidence in the formal health sector, either because they have had a bad experience at the local clinic or have heard that they can expect long waits, ineffective treatment, drug shortages, and rude or judgmental health workers. Others want to avoid the stigma associated with having an STD.
Unfortunately, patients' lack of confidence in the STD care provided by the formal health sector is often justified. The lack of rapid, inexpensive, accurate diagnostic tests for most STDs and shortages of drugs make it difficult for health care personnel in developing countries to provide quality care. Diagnosis by clinical guess, despite its inaccuracy, is probably the most common approach because laboratory support is unavailable, unaffordable or impractical. Many providers prescribe ineffective drugs because they lack information about local patterns of drug resistance or do not have access to effective but also more expensive drugs.
Until recently, despite the overwhelming evidence of their devastating impact on the health of women, children and youth, STDs have largely been ignored.
The need for expensive drugs is driven by the rapid spread of resistance to STD drugs. This global problem is exacerbated in developing countries by high levels of incomplete or incorrect treatment with antibiotics, which allow STD pathogens to develop resistance to the drugs. In most developing countries, resistance of gonococci to penicillin and tetracycline has reached levels that make their use in gonorrhea treatment unacceptable. Resistance to more expensive categories of drugs is already beginning to develop.
A New Approach
A fundamental strategy of STD control programs is the early detection and treatment of disease, preferably during the first encounter between the patient and the health system. In many countries, STD patients are seen more often in private facilities (private physicians, clinics or pharmacies) and primary health care settings than in specialized STD clinics.
An effective and efficient STD control program should promote not only appropriate treatment-seeking behavior but rapid, inexpensive, accurate case management that can be implemented on a large scale by health providers with diverse levels of expertise. Ideally, health care providers should be trained to provide diagnosis and treatment during the initial visit and without laboratory support.
The syndromic approach to STD case management is being adopted in many developing countries because it facilitates one-stop treatment of STDs. With this approach, clinicians base diagnosis on a group of symptoms and treat for all diseases that could cause the syndrome (see The STD-HIV Link). Cure rates after treatment using syndromic management are 92 percent for urethral discharge, up to 100 percent for genital ulcers, and 80 to 91 percent for vaginal discharge.
In developing countries, the need for integrated services is acute. Eighty to 90 percent of the population in most of these countries depend on primary health care services. Because so few facilities are available for care and gaining access to services is usually time-consuming, it is important to provide as many services as possible at each facility. When clients make the effort to obtain one service, the full range of preventive and curative care should be offered. In Tanzania, improved and integrated STD care through primary health care services reduced HIV incidence by 42 percent in one rural population in Tanzania (see Study Confirms Value of STD Treatment in Curbing HIV Transmission).
A nurse at a health center in Lima, Peru, talks to three mothers about their infants health. Integrating STD services with maternal and child health care is one option for improving women's access to STD diagnosis and treatment. (Jeremy Horner/UNICEF/93-BOU0705)
The individuals most at risk of sexually transmitted infection are often members of society's least powerful groups who are unlikely to have access to quality health care services. Programs that offer prevention education, condoms and affordable, effective diagnosis and treatment of STDs play a fundamental role in reducing the spread of STDs among these groups. In Calcutta, India, for example, an initiative that used peer education, condom distribution and provision of timely STD treatment in a red light district increased regular condom use among sex workers from almost zero to 42 percent in just one year. In Thailand, as a result of the government's 100 Percent Condom Program, the five major STDs declined by 69 percent among sex workers and their clients in four years.
Overlapping health care needs in the developing world provide a unique opportunity to deliver STDs and HIV/AIDS prevention and care alongside other health care services. Service-based approaches, such as those offered by PROFAMILIA, the family planning association of Colombia, have shown that integrating family planning and STD services is feasible and beneficial to clients. In fact, the number of clients served by PROFAMILIA continues to increase each year.
The extent and severity of STDs, especially among women, youth and children, and the interrelationships between STDs and HIV/AIDS suggest the need to include STD control in services such as maternal and child health care and family planning. Because of high clinic attendance in most developing countries, antenatal clinics may provide a particularly good opportunity to reduce the burden of STD and prevent HIV and other STDs.
Q. Monir Islam, MD, MPH, is the medical officer of the Family Planning and Population Unit of Family and Reproductive Health of the World Health Organization (WHO). Previously he was responsible for the Sexually Transmitted Diseases Programme of WHO'S Global Programme on AIDS.
The STD-HIV Link
HIV increases the duration of some STDS, and STDs enhance the transmission of HIV infection.
Sexually transmitted disease (STD) control has been an important AIDS prevention strategy for the past five years because infection with another STD is believed to increase the risk of transmitting or acquiring HIV. Many epidemiologic and biologic studies and one clinical trial of the impact of STD treatment on new HIV infections now support the hypothesis that STDs enhance HIV transmission.
In fact, it is estimated that the presence of an STD can increase the risk of HIV infection as much as tenfold.
Since the beginning of the AIDS epidemic, an association between STDs and HIV infection has been noted in the majority of epidemiologic studies that examined both. But these descriptive, snapshot (cross-sectional) studies were unable to establish which came first: HIV or another sexually transmitted infection.
A handful of prospective studies that followed people over time also found an association between having an STD and acquiring HIV infection. By demonstrating the temporal sequence of HIV and other STDs, these studies provide stronger evidence that STD increases HIV transmission.
The risk of HIV found in prospective studies was generally higher with genital ulcers (caused by syphilis, chancroid or herpes) than with vaginal or urethral discharge (gonorrhea or chlamydial infection). Since the discharge syndromes are more common than genital ulcer diseases, however, it is difficult to determine which has a greater impact on HIV transmission in a population.
The results of a community-based, randomized clinical trial published in August 1995 provide perhaps the clearest evidence so far that other STDs have a significant impact on HIV transmission. Researchers documented a 42 percent reduction in new HIV infections in communities where improved STD services were provided.
Biologic data to support these observational studies are accumulating. HIV has been identified in the genital tract and in secretions from genital ulcers in both men and women. Several studies have shown that the shedding of HIV in genital fluids is increased by exudates from and the inflammatory response to sexually acquired infections, making HIV-positive persons more infective when they have an STD. When women have gonococcal or chlamydial infection, there is a disproportionate increase in CD4 lymphocytes (the white blood cells targeted by HIV) in the endocervix, which is the site of those infections.
Several studies have shown that treating an STD can reduce the secretion of HIV. In one study, researchers could isolate HIV virus in only half as many HIV-positive men after treating them for gonorrhea. In another, there was a 100-fold decrease in the amount of virus that could be detected in the ejaculate of a man after treatment for chlamydial urethritis.
Compelling biologic and epidemiologic evidence suggests that STDs increase the efficiency of HIV transmission. By altering the host's immune response, HIV may in turn change the course of some STDs. Curing the common ulcerative disease chancroid in HIV-infected people, for example, usually requires a seven-day course of antibiotics rather than the normal single dose. Herpes virus infections and human papillomavirus (wart virus) infections also can be more severe in those who are HIV-positive. The effect of HIV on syphilis is not clear; no effect on gonorrhea, trichomoniasis or chlamydial infection has been found.
Thus, there appears to be a synergistic relationship between HIV and STDs. HIV increases the duration of some STDS, and STDs appear to enhance the transmission of HIV infection. Prevention and treatment of STDs are clearly critical strategies for HIV prevention.
- Gina Dallabetta
Gina Dallabetta, MD, is AIDSCAP's associate director of STD programs.